mirror of
https://github.com/ekeeke/Genesis-Plus-GX.git
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275 lines
7.5 KiB
C
275 lines
7.5 KiB
C
/***************************************************************************************
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* Genesis Plus
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* Sound Hardware
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*
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* Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003 Charles Mac Donald (original code)
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* Copyright (C) 2007-2012 Eke-Eke (Genesis Plus GX)
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*
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* Redistribution and use of this code or any derivative works are permitted
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* provided that the following conditions are met:
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*
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* - Redistributions may not be sold, nor may they be used in a commercial
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* product or activity.
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*
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* - Redistributions that are modified from the original source must include the
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* complete source code, including the source code for all components used by a
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* binary built from the modified sources. However, as a special exception, the
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* source code distributed need not include anything that is normally distributed
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* (in either source or binary form) with the major components (compiler, kernel,
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* and so on) of the operating system on which the executable runs, unless that
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* component itself accompanies the executable.
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*
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* - Redistributions must reproduce the above copyright notice, this list of
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* conditions and the following disclaimer in the documentation and/or other
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* materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************************/
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#include "shared.h"
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#include "blip_buf.h"
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/* FM output buffer (large enough to hold a whole frame at original chips rate) */
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static int fm_buffer[1080 * 2];
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static int fm_last[2];
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static int *fm_ptr;
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/* Cycle-accurate FM samples */
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static uint32 fm_cycles_ratio;
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static uint32 fm_cycles_start;
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static uint32 fm_cycles_count;
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/* YM chip function pointers */
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static void (*YM_Reset)(void);
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static void (*YM_Update)(int *buffer, int length);
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static void (*YM_Write)(unsigned int a, unsigned int v);
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/* Run FM chip until required M-cycles */
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INLINE void fm_update(unsigned int cycles)
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{
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if (cycles > fm_cycles_count)
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{
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/* number of samples to run */
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unsigned int samples = (cycles - fm_cycles_count + fm_cycles_ratio - 1) / fm_cycles_ratio;
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/* run FM chip to sample buffer */
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YM_Update(fm_ptr, samples);
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/* update FM buffer pointer */
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fm_ptr += (samples << 1);
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/* update FM cycle counter */
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fm_cycles_count += samples * fm_cycles_ratio;
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}
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}
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void sound_init( void )
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{
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/* Initialize FM chip */
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if ((system_hw & SYSTEM_PBC) == SYSTEM_MD)
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{
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/* YM2612 */
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YM2612Init();
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YM2612Config(config.dac_bits);
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YM_Reset = YM2612ResetChip;
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YM_Update = YM2612Update;
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YM_Write = YM2612Write;
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/* chip is running a VCLK / 144 = MCLK / 7 / 144 */
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fm_cycles_ratio = 144 * 7;
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}
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else
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{
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/* YM2413 */
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YM2413Init();
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YM_Reset = YM2413ResetChip;
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YM_Update = YM2413Update;
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YM_Write = YM2413Write;
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/* chip is running a ZCLK / 72 = MCLK / 15 / 72 */
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fm_cycles_ratio = 72 * 15;
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}
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/* Initialize PSG chip */
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SN76489_Config(0, config.psg_preamp, config.psgBoostNoise, 0xff);
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}
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void sound_reset(void)
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{
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/* reset sound chips */
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YM_Reset();
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SN76489_Reset();
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/* reset FM buffer ouput */
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fm_last[0] = fm_last[1] = 0;
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/* reset FM buffer pointer */
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fm_ptr = fm_buffer;
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/* reset FM cycle counters */
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fm_cycles_start = fm_cycles_count = 0;
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}
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int sound_update(unsigned int cycles)
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{
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int delta, preamp, time, l, r, *ptr;
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/* Run PSG & FM chips until end of frame */
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SN76489_Update(cycles);
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fm_update(cycles);
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/* FM output pre-amplification */
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preamp = config.fm_preamp;
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/* FM frame initial timestamp */
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time = fm_cycles_start;
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/* Restore last FM outputs from previous frame */
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l = fm_last[0];
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r = fm_last[1];
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/* FM buffer start pointer */
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ptr = fm_buffer;
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/* flush FM samples */
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if (config.hq_fm)
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{
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/* high-quality Band-Limited synthesis */
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do
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{
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/* left channel */
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delta = ((*ptr++ * preamp) / 100) - l;
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l += delta;
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blip_add_delta(snd.blips[0][0], time, delta);
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/* right channel */
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delta = ((*ptr++ * preamp) / 100) - r;
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r += delta;
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blip_add_delta(snd.blips[0][1], time, delta);
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/* increment time counter */
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time += fm_cycles_ratio;
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}
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while (time < cycles);
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}
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else
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{
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/* faster Linear Interpolation */
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do
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{
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/* left channel */
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delta = ((*ptr++ * preamp) / 100) - l;
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l += delta;
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blip_add_delta_fast(snd.blips[0][0], time, delta);
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/* right channel */
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delta = ((*ptr++ * preamp) / 100) - r;
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r += delta;
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blip_add_delta_fast(snd.blips[0][1], time, delta);
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/* increment time counter */
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time += fm_cycles_ratio;
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}
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while (time < cycles);
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}
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/* reset FM buffer pointer */
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fm_ptr = fm_buffer;
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/* save last FM output for next frame */
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fm_last[0] = l;
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fm_last[1] = r;
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/* adjust FM cycle counters for next frame */
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fm_cycles_count = fm_cycles_start = time - cycles;
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/* end of blip buffers time frame */
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blip_end_frame(snd.blips[0][0], cycles);
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blip_end_frame(snd.blips[0][1], cycles);
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/* return number of available samples */
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return blip_samples_avail(snd.blips[0][0]);
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}
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int sound_context_save(uint8 *state)
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{
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int bufferptr = 0;
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if ((system_hw & SYSTEM_PBC) == SYSTEM_MD)
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{
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bufferptr = YM2612SaveContext(state);
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}
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else
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{
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save_param(YM2413GetContextPtr(),YM2413GetContextSize());
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}
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save_param(SN76489_GetContextPtr(),SN76489_GetContextSize());
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save_param(&fm_cycles_start,sizeof(fm_cycles_start));
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return bufferptr;
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}
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int sound_context_load(uint8 *state)
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{
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int bufferptr = 0;
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if ((system_hw & SYSTEM_PBC) == SYSTEM_MD)
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{
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bufferptr = YM2612LoadContext(state);
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}
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else
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{
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load_param(YM2413GetContextPtr(),YM2413GetContextSize());
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}
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load_param(SN76489_GetContextPtr(),SN76489_GetContextSize());
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load_param(&fm_cycles_start,sizeof(fm_cycles_start));
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fm_cycles_count = fm_cycles_start;
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return bufferptr;
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}
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void fm_reset(unsigned int cycles)
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{
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/* synchronize FM chip with CPU */
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fm_update(cycles);
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/* reset FM chip */
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YM_Reset();
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}
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void fm_write(unsigned int cycles, unsigned int address, unsigned int data)
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{
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/* synchronize FM chip with CPU (on data port write only) */
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if (address & 1)
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{
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fm_update(cycles);
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}
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/* write FM register */
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YM_Write(address, data);
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}
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unsigned int fm_read(unsigned int cycles, unsigned int address)
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{
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/* synchronize FM chip with CPU */
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fm_update(cycles);
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/* read FM status (YM2612 only) */
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return YM2612Read();
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}
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